Cooking Condition - Wolf MWD24-2 Service Manual

Drawer Microwave

COOKING CONDITION

Program desired cooking time by touching the NUMBER pads. Program the power level by touching the POWER
LEVEL pad and then a number pad.
When the START pad is touched, the following operations occur:
1. The contacts of relays are closed and components connected to the relays are turned on as follows
(See the Schematic (Off Condition) diagram on page 3-15):
RELAY CONNECTED COMPONENTS
RY-1 Oven Lamp/Stir Fan Motor/Fan Motor
RY-2 Power Transformer
2. 20 vac is supplied to the primary winding of the power transformer and is converted to about 3.3 vac output on
the filament winding, and approximately 2370 vac on the high voltage winding.
3. The filament winding voltage heats the magnetron filament and the H.V. winding voltage is sent to a voltage dou-
bler circuit.
4. The microwave energy produced by the magnetron is channeled through the waveguide into the cavity feed-box,
and then into the cavity where the food is placed to be cooked.
5. Upon completion of the cooking time, the power transformer, oven lamp, etc. are turned off, and the generation
of microwave energy is stopped. The oven will revert to the OFF condition.
6. When the drawer is opened during a cook cycle, the monitor switch, door sensing switch, secondary interlock
switch, relay (RY) and primary interlock relay are activated with the following results. The circuits to the stir fan
motor, the cooling fan motor, and the high voltage components are de-energized, the oven lamp remains on, and
the digital read-out displays the time still remaining in the cook cycle when the door was opened.
7. The monitor switch electrically monitors the operation of the secondary interlock switch and secondary interlock
relay and is mechanically associated with the drawer so that it will function in the following sequence.
8. When the drawer opens from the closed position, the primary interlock relay (RY2) and secondary interlock
switch open their contacts. And contacts of the relay (RY) remains closed. Then the monitor switch contacts
close.
9. When the drawer is closed from the open position, the monitor switch contacts open first. Then the contacts of
the secondary interlock switch and door sensing switch close. And contacts of the relay (RY) open.
If the secondary interlock switch and primary interlock relay (RY2) fail with the contacts closed when the drawer is
opened, the closing of the monitor switch contacts will form a short circuit through the fuse, secondary interlock
switch, relay (RY) and secondary interlock relay (RY2), causing the fuse to blow.
POWER LEVEL P-0 TO P-90 COOKING:
When Variable Cooking Power is programmed, the 120 volts A.C. is supplied to the power transformer intermittently
through the contacts of relay (RY-2) which is operated by the control unit within 32 seconds time base. Microwave
power operation is as follows:
NOTE: The ON/OFF time ratio does not correspond with the percentage of microwave power, because approxi-
mately two (2) seconds are needed for heating of the magnetron filament.
(Models MWD24-2 / MWD30-2)
VARI-MODE
Power 10 (P-HI) (100% power)
Power 10 (P-90) (approx 90% power)
Power 10 (P-80) (approx 80% power)
Power 10 (P-70) (approx 70% power)
Power 10 (P-60) (approx 60% power)
Power 10 (P-50) (approx 50% power)
Power 10 (P-40) (approx 40% power)
Power 10 (P-30) (approx 30% power)
Power 10 (P-20) (approx 20% power)
Power 10 (P-10) (approx 10% power)
Power 10 (P-0) (0% power)
POWER LEVEL Cooking Conditions
ON TIME OFF TIME
32 sec.
30 sec.
26 sec.
24 sec.
22 sec.
18 sec.
16 sec.
12 sec.
8 sec.
6 sec.
0 sec.
3-13
Theory of Operation
0 sec.
2 sec.
6 sec.
8 sec.
10 sec.
14 sec.
16 sec.
20 sec.
24 sec.
26 sec.
32 sec.
#813632 - Revision B - December, 2009